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Trying to understand how magnetos work

B

brightlights

Well-known member
I just installed a battery switch on my newly acquired 435/480 convertion....Single battery......Dual mags......The isqallation is correct.....no loose ends.....

Going through normal operating procedures, the engine starts fine...However, after the engine is running, if i turn the battery switch to off with the mags on, the engine keeps running....If I switch the mags off, then engine shuts off......

Should'nt the engine stop if I turn off the battery switch?
 
Not with mags they have to be grounded to shut off the engine that's why you turn the switches upside down so down is off and up is on
 
as long as mag is on, u can hand start the engine by spinning the prop by hand. it will run till u either crash or turn off the mag.
 
Mags make their own power for spark, you have to stop them from making power to kill the engine. Dont turn your prop with the mag switch on or u/s, it could kill you or remove an arm.
 
Ok a little technical here , like an outboard theres a magnet that passes by a coil assy which causes an emf field that is induced into the windings of the coil.this voltage is then stepped up to between 20k and 50k volts when the br3reaker points open the field collapses and voltage finds its nearest path to ground I.e whether its the kill switch or key switch or spark plugs. Magneto is self generating hence why no batt is needed .in a nutshell thats the basics
 
Just a heads-up. Some alternators are sensitive to having the battery turned off while charging. It's like a hydraulic pump pushing against a closed head. I can't remember what part gets affected, diodes, rectifier or regulator? Some battery switches protect against this if you mistakenly switch off while running. That's assuming that you have a 1-wire alt. If it has a "field" wire, once activated, it will stay on. You can avoid this by wiring the alt charging wire directly to the battery/ies, with appropriate in-line fuse. You might want to check your alt and see if it's charging alright if it wasn't protected.
 
Alternator with battery disconnected can produce like a hundred volts depending on rpm it's turning. Could blow up bulbs, gauges, voltage regulator etc. some guys will actually wire them up so they can weld with them.
http://www.metalwebnews.com/information/alternator-welder.pdf
 
yobee said:
Would a mag work to zap fish, in a private pond of course?
Click to expand...
and of course don't forget the greatest invention ever for fishing......."the cordless drill motor"
 
Gary S said:
GMAC 76 said:
yobee said:
Would a mag work to zap fish, in a private pond of course?
Click to expand...
and of course don't forget the greatest invention ever for fishing......."the cordless drill motor"
Click to expand...

OK I'll bite, why a cordless drill motor?
Click to expand...


Im guessing because you can hook the drill up to a mag and spin the mag to make sure its firing correctly. just a shot in the dark though. :thumbleft:
 
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